Help with carb jetting

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Help with carb jetting

Postby Oldkwakaman » Wed Sep 04, 2019 3:33 pm

Howdy Kwaka blokes. I've just completed the resto of a bitsa 1974 Z1A / 1977 Z100 for a mate. To be more specific it is a 1977 Z1000 frame with all 1974 Z1A running gear. At some point in time the engine had a re-bore with Z1000 (70mm) pistons fitted. During the resto I had to go a further 0.5mm over size. It is fitted with VM28 carbs but I don't know how to tell if they are ss or not. Oh, it has Delcavic 4 into 1 exhaust. Not my preference but not my bike. The problem I'm having is that it's not running well at idle or at any given throttle position although it runs very well and pulls away without missing a beat when the power is turned on. Having said that it's not run in yet so I'm not able to give it too much stick. The carbs came to me fitted with 117.5 mains, 17.5 pilots, 5J9-2 needle and 2.25 cut away. As far as I can tell, from a very confusing manual, it should be more like 107.5 mains, 15 pilot 5CN15-3 needle and 1.5 cut away.
Can anyone out there in Kwaka world give me some advice on where I need to be with this beast. I'm getting a bit tired of messing around and getting nowhere.
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Re: Help with carb jetting

Postby billwest » Thu Sep 05, 2019 10:59 am

Hi Mate,

I would start with the idle mix screws, and set them at 2.5 turns out as a baseline.
Also, are the carbs balanced?
What colour are the plugs after running at idle?

Bill.
Don't ride as if you own the road.......
Ride as if you own the bike!

ZZR1200 ('02), ZRX1200S ('01).
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Re: Help with carb jetting

Postby BrettZZR » Thu Sep 05, 2019 5:32 pm

If all else fails, I have heard that the mech at Mack1 Kawa in Wangara is a gun with carbs? Can't say I know, but that is what I have heard...

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